This study is a longitudinal comparison of social and familial influences on child development among children in four different ethnic groups: Chinese, Puerto Rican, American Black, and Non- Hispanic White. The design capitalizes on a preliminary study, currently underway, that is gathering data on ethnic differences in life-style, psychological factors, and medical care during pregnancy. We propose to continue to follow, after delivery, a sub-sample (N=50 in each ethnic group) of women and their newborn children, randomly selected from the original antenatal sample (N=200 in each ethnic group). The study will assess maternal, familial, and social-contextual differences and similarities among the four groups, both cross-sectionally and longitudinally (i.e., stability of measures over time). Furthermore, we will describe variations in child care practices (including maternal interactive behaviors and interactive aspects of the proximal home environment), both within and across ethnic groups, to determine how they mediate developmental processes. Most importantly, we will examine the conditioning effect of acculturation on all proximal and distal determinants of child outcome, and the interrelationships among the variables. The antecedent variables include measures of maternal depressive symptoms, social support networks (assessed multi-dimensionally using a variety of instruments), stressful life events, chronic strains, and functional components of the social environment (such as family structure, degree of crowding, child-spacing, etc.). Mediating variables include child care practices, as defined by observed maternal interactive behaviors (laboratory assessments) and observed dimensions of the home environment. Dependent variables include a measure of cognitive development, behavior problems, attachment, and observed child competencies (laboratory assessments). In addition, we will control for socioeconomic level, as well as a number of dempgraphic factors. The cohort will be followed for two years; outcome will be assessed at 12 and 24 months. Particular advantages of the study include the use of instruments that have been pilot-tested in multi-ethnic samples, the linking of antenatal and postnatal data, and the systematic treatment of acculturation as a determinant of ethnic lifestyle patterns, with implications for child developmental processes.